Hybrid frequency modulation passive working point control method of non-balance interference measurement system

Abstract

The invention discloses a passive working point control method for modulating hybrid frequency of non-balance interference measurement system. The passive working point control method comprises error signal extraction and compensation signal generation. An error signal is extracted from a single-path interference signal through a mode of directly modulating a light source with a high frequency; a compensation signal is generated through a mode that a low frequency control signal directly modulates the light source to eliminate a phase drift; and an interference light source frequency is directly regulated through cooperation between a high frequency modulation signal and a low frequency modulation signal. The passive working point control method realizes passive control of an interference closed-loop sensing working point and guarantees that an interference measurement system to always work in a most sensitive linear area. The passive working point control method is totally based on an original interference system, solves a phase drift problem while guaranteeing reliability and stability of the system, and provides a new passive closed-loop working point control method to an interference signal demodulation scheme. The passive working point control method is applicable to the demodulation work of an interferometric sensor.

Description

Technical field: [0001] The invention relates to an interferometric demodulation algorithm, in particular to a passive operating point control method for mixed frequency modulation of an unbalanced interferometric system, which belongs to the field of optics. Background technique: [0002] Phase drift is a common problem in interferometry, which has a huge impact on the accuracy of demodulation results. The phase drift is mainly due to the random change of the initial phase of the interferometer induced by the superposition of external environment changes and its own unstable factors, causing the system operating point to deviate from the orthogonal operating point, resulting in fluctuations, fading or even disappearance of the demodulated signal. In order to accurately recover the signal to be measured from the interference signal, a variety of demodulation algorithms have emerged. The closed-loop operating point control method is one of many demodulation algorithms. Throu...

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Problems solved by technology

[0003] The traditional closed-loop operating point control method refers to introducing piezoelectric ceramics as phase modulators in the reference optical path of interferometric sensors, and generating compensation signals through the displacement of piezoelectric ceramics. Due to the introduction of active devices, the reliability and reliability of the system are greatly reduced. stability, which increases the complexity of the system; at the same time, the method requires the interferometer to output two complementary interference signals to generate the phase tracking signal, which greatly limits the universality of the method

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